File extensions – definition and basic information


File extensions are the integral parts of the files that are on each computer. Often, when working on a computer, we encounter a wide range of files, such as docx, ppt, part, mp3 or rmvb. We realize that they are there – but we often do not know what they are for on our computer.

File extension, also known as the filename extension is a suffix added to the name of a computer file, usually consisting of a number of characters placed after the last dot in the filename, which gives us information about its coding. In other words a file extension is a file format. It allows the operating system (e.g. Windows) to recognize what program it should try to open the file.

In the table below you will find a random selection of popular file extensions.


File extension The full name of the file Category

7Z file extension

7-Zip Compressed File

Compressed Files

TARGZ file extension

Compressed Tarball File

Compressed Files

SLN file extension

Visual Studio Solution File

Developer Files

TEX file extension

LaTeX Source Document

Text Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

SYS file extension

Windows System File

System Files

PKG file extension

Mac OS X Installer Package

Compressed Files

KEY file extension

Keynote Presentation

Data Files

HTM file extension

Hypertext Markup Language File

Web Files

LOG file extension

Log File

Text Files

ASF file extension

Advanced Systems Format File

Video Files

PAGES file extension

Pages Document

Text Files

C file extension

C/C++ Source Code File

Developer Files

PDB file extension

Program Database

Database Files

VCF file extension

vCard File

Data Files